Gas/liquid phase separator and the fuel cell-based power production unit equipped with one such separator

ABSTRACT

A gas and liquid phase separator apparatus and an apparatus for energy production based on fuel cells within the phase separator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gas and liquid phase separator aswell as to an assembly for energy production based on fuel cells, whichis provided with such a phase separator.

2. Related Art

Gas and liquid phase separators are used in many industrialapplications, especially in the field of energy production based on fuelcells.

Conventionally, an assembly for energy production based on fuel cellscomprises a cell block, which has an anode compartment in which theoxidation of hydrogen takes place, as well as a cathode compartment inwhich the oxygen in air is reduced, with water being produced.

It is in this case known to provide a gas separator downstream of thecathode compartment, making it possible to separate the oxygen-depletedair and the water which are discharged from this cathode compartment. Itis also possible to provide another phase separator in the outlet lineof the anode compartment, which carries a mixture of hydrogen and water.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a phase separator which isadvantageous in terms of compactness and which can be used, inparticular but not exclusively, in an assembly for energy productionbased on fuel cells.

To this end it relates to a gas and liquid phase separator comprising abody, an inlet for a diphasic mixture containing gas and liquid to beseparated, a gas outlet and a liquid outlet, characterized in that itfurthermore comprises a hydrophilic structure which is arranged in thebody and delimits an internal space and an external space with respectto this body, in that means are provided for creating vortices in thediphasic mixture when it is flowing through said internal space, so asto recover the liquid against the walls of said hydrophilic structure,in that the gas outlet is in communication with the internal space, andin that the liquid outlet is in communication with the external space.

According to other characteristics of the invention:

-   -   the means for producing vortices comprise a profiled auxiliary        member, in particular an impeller;    -   the means for producing vortices consist of said hydrophilic        structure.

The invention also relates to an assembly for energy production based onfuel cells, comprising a fuel cell block which has a cathodecompartment, an anode compartment, at least two gas feed circuits and atleast two discharge circuits, each of which makes it possible todischarge a mixture of gas and water from the cell block, this assemblybeing characterized in that at least one discharge circuit leads into agas and liquid phase separator as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood more clearly on reading the followingdescription, which is given solely by way of nonlimiting example andrefers to the appended drawings, in which:

FIG. 1 is a schematic view illustrating an assembly for energyproduction based on fuel cells, which is equipped with a phase separatoraccording to the invention;

FIG. 2 is a view in diametral section illustrating this phase separatormore precisely;

FIG. 3 is a view in section similar to FIG. 2, illustrating a phaseseparator according to a first alternative embodiment of the invention;

FIG. 4 is a view in section on the line IV—IV in FIG. 3;

FIG. 5 is a view in section similar to FIGS. 1 and 2, illustrating aphase separator according to another alternative embodiment of theinvention; and

FIG. 6 is a view in section on the line VI—VI in FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENTS

The energy production assembly schematically represented in FIG. 1comprises a fuel cell block, which has a cathode 2 as well as an anode(not shown).

This cathode compartment 2 receives an air feed circuit 6 at an inlet 4.A circuit 8 furthermore makes it possible to discharge a mixture ofoxygen-depleted air and water from the outlet 10 of this cathode.

The discharge circuit 8 leads into a separator 12, making it possible toseparate the gas and liquid phases of the aforementioned mixture. A line14 makes it possible to recycle the water separated from this mixtureback to the inlet of the cathode 2. The separated gas phase, essentiallyconsisting of oxygen-depleted air, is furthermore discharged via a line16.

The fuel cell block is also equipped with two additional circuits (notshown), respectively for supplying the anode with hydrogen and fordischarging the depleted hydrogen mixed with water from this anode. Thisdischarge circuit may also lead into another phase separator (not shown)similar to the one 12.

Referring now to FIG. 2, the phase separator 12 comprises an inlet 18placed in communication with the discharge circuit 8. This tubular inlet18 extends into a cylindrical body 20, which is coaxial with this inletbut has a larger diameter.

The body 20 ends in an outlet 22, which is coaxial with the inlet 18 andhas a similar diameter. This body contains a hydrophilic membrane 24,which is arranged so as to form a cylinder coaxial with the inlet 18 andthe outlet 22, and with the same diameter as them. The membrane 24, forexample made of polyethylene or nylon, is to this end held in place byseals and clamping.

This membrane hence defines two spaces in the body of the separator,respectively an internal space 26 and an external space 28.

The external space 28, which is annular, is placed in communication witha radial outlet 30 with which the body 20 is provided. This outlet 30,which makes it possible to discharge the water, as will be explainedbelow, leads into the recycling line 14.

A coalescer pad 32 of the known type is arranged in the inlet 18 of theseparator 12. It makes it possible to increase the size of the waterdroplets to be recovered, so as to improve their separation.

Downstream of this pad 32, in the example which is represented, animpeller 34 is provided which is arranged immediately upstream of thehydrophilic membrane 24. This impeller makes it possible to createvortices in the flow of gas and water taken in through the inlet 18.

The mixture hence follows along an approximately helicoid path in theinternal space 26, which is indicated by the arrows F. As a variant,such vortices may also be induced by replacing the impeller 34 with atangential gas inlet.

In this way, because of the centrifugal force, the water initiallypresent in the mixture becomes pressed against the internal walls of themembrane 24, which hence carries out the recovery of this water.

It is discharged by means of the radial outlet 30. The quality of thisdischarge may be improved by keeping the pressure in the external space28 at a value lower than that prevailing in the internal space 26.

To this end, suction may be applied to the water at the outlet 30, forexample by pumping. As a variant, it is also possible to utilize thepressure difference naturally existing between these internal andexternal spaces, 26 and 28 respectively.

The membrane 24 is such that its bubble point is higher than thepressure difference existing between the internal space 26 and theannular external space 28 during operation. This makes it possible toavoid any passage of gas toward this external space 28, so that only thewater is present therein.

FIGS. 3 and 4 illustrate a first alternative embodiment of theinvention. In these figures, the mechanical elements which are identicalto those in FIG. 2 are assigned the same reference numbers, to which 50has been added.

The separator 62 in these FIGS. 3 and 4 differs from the one 12 in FIG.2 firstly in that the membrane 74 does not have a cylindrical profile.

Specifically, as shown by FIG. 4, this membrane 74 is involute, orfolded, as viewed in a section transverse to the flow of the mixture.This makes it possible to increase the contact area of this membrane,and therefore to improve the separation.

Furthermore, an additional membrane 86 is arranged in the internal space76 delimited by the primary membrane 74. This membrane 86 thereforeseparates this internal space 76 into a central region 88 and anintermediate region 90, which is annular.

The bubble point of the secondary membrane 86 is advantageously higherthan the pressure difference existing between the central region 88 andthe intermediate region 90. It should be noted that this pressuredifference ensures substantially integral recovery of the waterinitially present in the central region 88. This hence avoids stagnationof this water in this region 88, and guarantees efficient separation.

A purge (not shown) may be provided on the walls of the body 70, so asto feed into the intermediate region 90. Such a purge makes it possibleto discharge the air present in this intermediate region 90, andtherefore to prevent this air from remaining trapped and blocking theseparator.

The primary membrane 74, the bubble point of which is higher than thatof the secondary membrane 86, lastly ensures recovery of all the watertaken in through the inlet 68. This water is subsequently dischargedthrough the outlet 80, in a manner similar to that which was describedwith reference to FIG. 2.

It should be noted that, in the exemplary embodiment of the FIGS. 3 and4, the pressure prevailing in the central region 88 is slightly higherthan that of the intermediate region 90, which is itself much higherthan that prevailing in the external space 78.

FIGS. 5 and 6 illustrate another alternative embodiment. In thesefigures, the mechanical elements which are similar to those in FIG. 2are assigned the same reference numbers, to which 100 has been added.

The separator 112 in FIGS. 5 and 6 differs from the one in FIGS. 2 to 4in that it does not have an impeller. Specifically, the turbulentmovement of the flow of water and gas taken in through the inlet 118 isensured by the actual configuration of the hydrophilic membrane 124.

Here, the latter has a folded or multilobed, or involute shape, asviewed in a section transverse to the flow direction of the mixture ofwater and gas. It should be noted that the shape of the folds of themembrane is such that they leave a central free section 125 remaining,the transverse dimension of which is particularly small.

Furthermore, as viewed from the side in FIG. 5, the membrane 124 alsohas a spiral arrangement, i.e. its forms a helix overall. In this way,the mixture of water and air taken in through the inlet 118 flows alonga vortex as it progresses along the membrane 124.

The embodiment of these FIGS. 5 and 6 is more particularly advantageousin economic terms. This is because it makes it possible to combine twoseparate functions in a single membrane, namely those of creatingvortices as well as recovering the water.

The invention makes it possible to achieve the objects mentioned above.

This is because the phase separator according to the invention has asimple structure, and employs a small number of constituent elements.

Furthermore, the use of a hydrophilic membrane makes it possible todivide this separator into two separate compartments, which arerespectively intended for discharging the water and the gas. In thisway, the compartment reserved for the water can be provided with a lowerpressure, which guarantees particularly efficient recovery thereof.

It will be understood that many additional changes in the details,materials, steps and arrangement of parts, which have been hereindescribed in order to explain the nature of the invention, may be madeby those skilled in the art within the principle and scope of theinvention as expressed in the appended claims. Thus, the presentinvention is not intended to be limited to the specific embodiments inthe examples given above.

1. A gas and liquid phase separator apparatus, comprising: a) acylindrical body, b) an inlet for a two-phase mixture, c) at least onegas outlet, d) a liquid outlet, e) at least one means to producevortices, and f) at least one hydrophilic membrane, wherein saidmembrane is located within said body, and wherein said membrane dividessaid body into an internal and an external space, wherein said gasoutlet is connected to said internal space, and wherein said liquidoutlet is connected to said external space.
 2. The apparatus accordingto claim 1, wherein said means to produce vortices comprise a profiledauxiliary member.
 3. The apparatus according to claim 2, wherein saidprofiled auxiliary member is an impeller.
 4. The apparatus according toclaim 1, wherein said membrane produces said vortices.
 5. The apparatusaccording to claim 4, wherein said membrane extends along a spiral andhas a folded shape.
 6. The apparatus according to claim 1, wherein saidapparatus further comprises an additional hydrophilic membrane, whereina secondary hydrophilic membrane is located in said internal space, andwherein said internal space is divided into a central and anintermediate region.
 7. The apparatus according to claim 6, wherein saidintermediate region comprises an outlet for purging the gas in saidregion.
 8. The apparatus according to claim 6, wherein said secondarymembrane has a bubble point lower than a primary hydrophilic membrane.9. The apparatus according to claim 1, wherein said inlet and gas outletare coaxial, with reference to the flow direction of the two-phasemixture, and wherein said liquid outlet is radial.
 10. A method toseparate a diphase mixture in a phase separator comprising the steps of:a) feeding said mixture into at least one inlet; b) deflecting saidmixture into a hydrophilic membrane, wherein said membrane is locatedwithin said body, and wherein said membrane divides said body into aninternal and external space, c) creating vortices in said mixture whenit flows through said internal space; and d) recovering a liquid fromthe walls of said hydrophilic membrane.
 11. An integrated energyproducing apparatus comprising: a) at least on fuel cell comprising: 1)anode and cathode compartments, 2) at least two gas feed inlets, and 3)at least two discharge outlets, and b) at least one two phase separatorcomprising: 1) a cylindrical body, 2) an inlet for a two-phase mixture,3) at least one gas outlet, 4) a liquid outlet, 5) at least one means toproduce vortices, and 6) at least one hydrophilic membrane, wherein saidmembrane is located within said body, and wherein said membrane dividessaid body into an internal and an external space, wherein said gasoutlet is connected to said internal space, and wherein said liquidoutlet is connected to said external space.
 12. The apparatus accordingto claim 11, wherein said discharge outlets are connected to saidseparator.
 13. The apparatus of claim 1, wherein said means to producevortices is disposed immediately upstream of said hydrophilic membrane.